Oxyaminations 2-amino alcohol

Nitrogen-transfer reactions of osmium imido species lead to cis diamines or amino alcohols. Reaction of 0s02(N-/-C4H9)2 [63174-13-0] with olefins produces vicinal diamines after reductive cleavage. Catalytic oxyamination of olefins using chloramine-T or AJ-chlor-AJ-argenocarbamates yields vicinal hydroxy toluenesulfonamides (112) or carbamates (113), respectively, which maybe deprotected to vicinal amino alcohols. 

The same researchers found that imino derivatives of Os04 react with alkenes to produce cis-jS-amino alcohols (equation 124).346,347 This oxyamination reaction can be made catalytic in the presence of chloramine salts, e.g. ArS02NClNa or ROCONClAg.348,349... 

The complexes will effect oxyamination reaction with alkenes in a stereospecific reaction (Scheme 8).290 After reductive cleavage of the intermediate alkanolaminato complex (I) (see below) vicinal amino alcohols (II) are formed. The reaction is unusual in that the new C—N bond is always formed at the least substituted terminal alkenic carbon atom, and there is a clear preference for the imido complex to use its NR group for coordination to the osmium despite the steric restraints of R.299,300 However, the least sterically hindered part of the alkene moiety is attached to. the nitrogen atom.290,291,300 The yields of amino alcohols in the reaction can be improved by addition of tertiary alkyl bulkhead amines (see below). 

By treating the azasulfenylation products with trimethyloxonium tetrafluoroborate, sulfonium salts 5 were obtained, which in acetonitrile at 80 °C underwent decomposition to give the corresponding 4,5-dihydro-l,3-oxazole 6 in good yield. Successive hydrolysis afforded the amino alcohol 7, so that the overall sequence consists of a cis oxyamination of a double bond. 

When chiral amines are used in the oxyamination reaction, stereogenicity is induced in the amination step and in this way optically active amino alcohols are obtained after oxidation69. An optically active secondary or tertiary amine can be used as a ligand for palladium in the intermediate 7t-complex, to which an excess of an achiral amine can be added (reagent-induced diastereoselectivity). Here, a pair of diastereomeric tt-complexes are formed which may be in equilibrium with each other, the degree of asymmetric induction is dependent on the ratio between the diastereomeric complexes and/or on their different reactivity. 

Oxyamination. The ratio of amino alcohol to diol formed by reaction of alkenes with the reagent is considerably improved by the presence of tertiary alkyl bridgehead amines. Of these ligands, quinuclidine (1, 976 4, 417) is the most efficient. In this case DME is used in place of pyridine as solvent. 

Using the simple trick devised by Seebach et ai, all nitro alcohol derivatives can be prepared dia-stereoselectively in a complementary fashion, and even p-amino alcohols, which cannot be prepared by oxyamination of alkenes, are accessible. 

Oxyamination of olefins. This reagent reacts with a variety of olefins to give, after reductive cleavage of intermediate osmate esters, cis-vicinal amino alcohols in fair to high yield. The reaction is regiospecific in that the new C—N bond is formed at the least substituted carbon atom of the olefin. The reagent reacts more rapidly with monosubstituted olefins than with di- and trisubstituted olefins. Diols are obtained as the main products from hindered olefins. Methylene chloride or THF can be used as solvents, but pyridine is the solvent of choice. 

The palladium-catalysed oxyamination of olefins is well known, and it has now been found that, by the use of chiral reagents, asymmetry can be induced in the amination step and that optically active tertiary amino-alcohols result. 1-Piperidino-l-trimethylsilyloxycyclopropane and the corresponding 1-hydroxy-compound have been prepared and examined for their utility as cyclopropanone equivalents. ... 

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